"I... hope that ways can be found to reduce current tensions through dialogue," International Atomic Energy Agency director general Yukiya Amano said in a speech opening the agency's quarterly board of governors meeting.

On May 8, Iran announced it no longer considered itself bound to keep to the limits of stocks of heavy water and enriched uranium which were agreed as part of the 2015 Joint Comprehensive Plan of Action (JCPOA).

Tehran's move came a year after US President Donald Trump pulled out of the deal. Washington has also reinforced economic sanctions against the Islamic republic.

Iran has also said that if the other parties to the JCPOA do not speed up work on mitigating the effects of US sanctions, by early July it may stop abiding by restrictions on the level to which it can enrich uranium and on modifications to its Arak heavy water reactor.

Two weeks ago, the latest inspections report by the IAEA said that while stocks of uranium and heavy water had increased, they were still within the limits set by the JCPOA.

"As I have constantly emphasised, the nuclear-related commitments entered into by Iran under the JCPOA represent a significant gain for nuclear verification," Amano said.

"It is essential that Iran fully implements its nuclear-related commitments under the JCPOA," he added.

The latest IAEA report noted that "technical discussions... are ongoing" with Iran in relation to its installation of up to 33 advanced IR-6 centrifuges, but did not specify the content of these discussions.

Also on Monday, German Foreign Minister Heiko Maas held talks with his Iranian counterpart Mohammad Javad Zarif in Tehran on the future of the JCPOA.

Maas acknowledged that the economic benefits Tehran hoped for from the deal were now "more difficult to obtain" but urged Iran to fully respect the agreement.

The JCPOA was struck between Iran and six major powers -- Britain, China, France, Germany, Russia and the United States -- in 2015.

Tensions between Washington and Tehran have worsened in recent weeks.

The United States has beefed up its military presence in the Middle East in response to alleged threats from the Islamic republic.